As illustrated in FIG. 1, a known differential temperature sensor 1 between a hot source Sc and a cold source Sf of the state of the art comprises:                a substrate (not shown), preferably made of a silicon-based material,        an assembly of thermoelectric layers arranged on the substrate separated by a thermally-insulating material 102, the assembly comprising at least one first junction 10 of a thermocouple 100, 101 on one side of the assembly, called hot side, and at least one second junction 11 of thermocouple 100, 101 on the opposite side of the assembly, called cold side,        at least one first and one second connection pads (not shown) arranged to transfer heat respectively to each first junction 10 and to each second junction 11.        
Terms “hot” and “cold” are to be understood in relative fashion, that is, the temperature of the “hot” source is higher than the temperature of the “cold” source.
The connection pads are intended to be thermally connected to hot source Sc and to cold source Sf.
The assembly of thermoelectric layers comprises N thermocouples 100, 101, that is, N layers based on a first thermoelectric material 100 and N layers based on a second thermoelectric material 101. Each first junction 10 and each second junction 11 are formed with an electrically-conductive material.
Output voltage V generated by sensor 1 is provided by the following formula:V=N×(S2−S1)×(Tc−Tf), where:                N is the number of thermocouples 100, 101,        S1 and S2 respectively are the Seebeck coefficient of the first and second thermoelectric materials 100, 101,        (Tc−Tf) is the thermal gradient applied between the hot side and the cold side of the assembly.        
Such a sensor 1 of the state of the art forms a chip and falls within thin layer technologies, thus differing from macroscopic Seebeck effect thermoelectric sensors.
“Chip” means a wafer, preferably made of silicon, comprising an elementary component.
Such a sensor 1 of the state of the art is thus used in various applications where a miniaturization is desired. One can mention, as non-limiting examples, microelectronics, mobile telephony, smart homes, smart buildings, smart grids, or certain industrial processes.
Further, non-integrated planar sensors capable of measuring the temperature of a flow orthogonal to the substrate are known in the state of the art, particularly from documents WO 2007034048, FR 2955708, WO 8402037, and FR 2598803.
Currently, to achieve an electronic function, the integration of such a sensor 1 to other elementary components in a circuit is performed during the circuit manufacturing technological process. This solution is not satisfactory since it introduces complexity and multiple constraints for the execution of the method steps, which have to take into account the influence of adjacent elementary components.
Further, the direct integration of such a sensor 1 in a package, for example, an integrated circuit package, causes significant heat losses which affect the thermal gradient applied between the hot side and the cold side of the assembly, thus preventing sensor 1 from operating properly.